1221510161 has 2 divisors, whose sum is σ = 1221510162. Its totient is φ = 1221510160.

The previous prime is 1221510149. The next prime is 1221510203. The reversal of 1221510161 is 1610151221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1198890625 + 22619536 = 34625^2 + 4756^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221510161 - 2¹⁰ = 1221509137 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221519161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610755080 + 610755081.

It is an arithmetic number, because the mean of its divisors is an integer number (610755081).

Almost surely, 2^1221510161 is an apocalyptic number.

It is an amenable number.

1221510161 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221510161 is an equidigital number, since it uses as much as digits as its factorization.

1221510161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120, while the sum is 20.

The square root of 1221510161 is about 34950.1095992559. The cubic root of 1221510161 is about 1068.9704368622.

Adding to 1221510161 its reverse (1610151221), we get a palindrome (2831661382).

The spelling of 1221510161 in words is "one billion, two hundred twenty-one million, five hundred ten thousand, one hundred sixty-one".